Theory Of Operation

The Manifold Absolute Pressure (MAP) Sensor is a transducer that varies resistance according to pressure changes in the Intake Manifold. The MAP Sensor signal provides the Powertrain Control Module (PCM) with an indication of the current air pressure within the Intake Manifold. The PCM uses this information to help calculate fuel delivery. The MAP Sensor functions as a typical three wire sensor. The PCM supplies 5 volts to the MAP Sensor on a 5 volt reference circuit and provides a ground on a low reference circuit. The MAP Sensor provides a voltage signal to the PCM on a signal circuit relative to the pressure changes. The PCM receives the Barometric Pressure (BARO) Sensor reading from the MAP Sensor with the ignition on, before the engine is cranking or running.